Abstract: A method for manufacturing an optical preform via an internal vapour deposition process, wherein during the inside deposition process the velocity of the reaction zone is set so that the velocity of the reaction zone over the length of the supply side-to-discharge side is higher than the velocity of the reaction zone over the length of the discharge side-to-supply side.

Abstract: A method for manufacturing a preform for optical fibers by a vapor deposition process wherein an intermediate step is carried out between one deposition phase and the next deposition phase(s), wherein the intermediate step includes supplying an etching gas to the supply side of the hollow substrate tube.

Abstract: The present invention relates to a method for manufacturing a primary preform for optical fibres, using an internal vapour deposition process, wherein a gas flow of doped undoped glass-forming gases is supplied to the interior of a hollow substrate tube having a supply side and a discharge side via the supply side thereof, wherein deposition of glass layers on the interior of the substrate tube is effected as a result of the presence of a reaction zone.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process, including the steps of: i) providing a hollow glass substrate tube having a supply side and a discharge side, ii) surrounding at least part of the hollow glass substrate tube by a furnace, iii) supplying doped or undoped glass-forming gases to the interior of the hollow glass substrate tube via the supply side thereof, iv) creating a reaction zone in which conditions such that deposition of glass will take place on the interior of the hollow glass tube are created, and v) moving the reaction zone back and forth along the length of the hollow glass substrate tube between a reversal point located near the supply side and a reversal point located near the discharge side of the hollow glass substrate tube, wherein, during at least part of step v), the gas flow comprises a first concentration of fluorine-containing compound when the reaction zone is moving in the direction of the discharge side.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process, including the steps of: i) providing a hollow glass substrate tube having a supply side and a discharge side, ii) surrounding at least part of the hollow glass substrate tube by a furnace, iii) supplying a gas flow, doped or undoped, of glass-forming gases to the interior of the hollow glass substrate tube via the supply side thereof, iv) creating a reaction zone in which conditions such that deposition of glass will take place on the interior of the hollow glass tube are created, and v) moving the reaction zone back and forth in longitudinal direction over the hollow glass substrate tube between a reversal point located near the supply side and a reversal point located near the discharge side of the hollow glass substrate tube.

Abstract: The present invention relates to an apparatus for carrying out a PCVD process in which one or more doped or undoped glass layers are coated onto the interior of a glass substrate tube. The apparatus comprises an applicator having an inner wall and an outer wall and a microwave guide that opens into the applicator. The applicator extends around a cylindrical axis and which is provided with a passage adjacent to the inner wall, through which the microwaves supplied via the microwave guide can exit, over which cylindrical axis the substrate tube can be positioned, while the applicator is fully surrounded by a furnace that extends over the cylindrical axis.

Abstract: A method for manufacturing a preform for optical fibers by means of a vapor deposition process, wherein plasma conditions are created and wherein the plasma is moved back and forth along the longitudinal axis of the hollow substrate tube between a reversal point near the supply side and a reversal point near the discharge side of the hollow substrate tube, so that the location where the soot deposition associated with one phase takes place is axially spaced from the location where the soot deposition associated with the other phase(s) takes place.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace set at a temperature T0, supplying doped or undoped gases via the supply side, creating a reaction zone to promote deposition, and moving the zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form at least one preform layer, which at least one layer comprises several glass layers.

Abstract: A method for manufacturing a primary preform for optical fibres using an internal vapour deposition process including the steps of providing a substrate tube having supply and discharge sides, surrounding at least part of the tube by a furnace, supplying glass-forming gases to the interior of the tube via the supply side, creating a reaction zone with conditions such that deposition of glass will take place on the inner surface of the tube, and moving the reaction zone back and forth along the length of the tube between reversal points near the supply and discharge sides to form one or more preform layers on the inner surface of the tube, wherein both reversal points are surrounded by the furnace.

Abstract: The present invention relates to a device for manufacturing an optical preform by means of an internal vapour deposition process, said device comprising an energy source and a substrate tube, which substrate tube comprises a supply side for supplying glass-forming precursors and a discharge side for discharging constituents that have not been deposited on the interior of the substrate tube, said energy source being movable along the length of the substrate tube between a point of reversal at the supply side and a point of reversal at the discharge side.

Abstract: The present invention relates to an apparatus for carrying out a PCVD deposition process, wherein one or more doped or undoped layers are coated onto the interior of a glass substrate tube, which apparatus comprises an applicator having an inner and an outer wall and a microwave guide which opens into the applicator, which applicator extends around a cylindrical axis and which is provided with a passage adjacent to the inner wall, through which the microwaves can exit, over which cylindrical axis the substrate tube can be positioned, and wherein at least one choke of annular shape having a length l and a width w is centred around the cylindrical axis within the applicator.

Abstract: The present invention relates to a device for manufacturing an optical preform by means of an internal vapour deposition process, said device comprising an energy source and a substrate tube, which substrate tube comprises a supply side for supplying glass-forming precursors and a discharge side for discharging constituents that have rot been deposited on the interior of the substrate tube, said energy source being movable along the length of the substrate tube between a point of reversal at the supply side and a point of reversal at the discharge side.

Abstract: A method for manufacturing an optical fiber preform is described that includes detecting structural integrity of the tube during a collapsing phase utilizing a fluid flow that is fed to the tube. Also, a system for manufacturing optical fiber preforms is described that comprises a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, and a fluid supply system configured to supply a fluid to the tube held by the holder. The system comprises a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring the fluid.

Abstract: A method is described for manufacturing an optical fiber preform, including a tube collapsing phase, and including monitoring the concentration of at least one fluid component of a fluid that is exhausted from the tube, to detect structural integrity of the tube. A system is also described for manufacturing optical fiber preforms. The system comprising a holder configured to hold a tube, a heater configured to heat at least part of the tube to a tube collapsing temperature, a fluid exhaust configured to discharge fluid from the tube, held by the holder. The system also includes a tube integrity monitor configured to monitor structural integrity of the tube, during a collapsing phase, by monitoring fluid that is discharged from the tube.

Abstract: The present invention relates to an apparatus for carrying out a plasma chemical vapor deposition process by which one or more layers of doped or undoped silica can be deposited on the interior of an elongated glass substrate tube. The present invention further relates to a method for manufacturing an optical fiber using such an apparatus.

Abstract: Disclosed is a method and device for manufacturing an optical preform. The method includes supplying dopant-containing glass-forming gases to the interior of a hollow glass substrate tube. Furthermore, the supply flow of dopant-containing glass-forming gases includes a main gas flow and one or more secondary gas flows. The secondary gas flows are divided into subflows, which are supplied to the interior of the hollow glass substrate tube together with the main gas flow. The method further includes effecting deposition of glass layers on the interior surface of the hollow glass substrate tube.

Abstract: The present invention relates to a method and a device for manufacturing optical performs, in which one or more layers of glass, doped or undoped, are deposited onto the internal surface of a hollow substrate tube, which deposition is effected by supplying one or more reactive gas mixtures of glass-forming compounds tot the interior of the hollow substrate tube and subsequently generating a non-isothermal plasma in the hollow substrate tube, after which the preform is subjected to a contraction process for the purpose of forming a massive rod, from which optical fibres are drawn.

Abstract: A device for applying, in use, electromagnetic microwave radiation in a plasma cavity. The device includes a plasma cavity present within a housing, being substantially cylindrically symmetric about a first axis, and which plasma cavity includes a cylindrical wall provided with a circumferential slit. The plasma cavity is in communication, via the slit, with a first end of an elongated microwave guide having a longitudinally extending second axis. The device is in communication in use with a microwave generating device via the other end of the microwave guide, in which the electromagnetic microwave radiation being generated may include several modes, where the device can, in use, generate microwave radiation in the slit, which microwave radiation has only one electromagnetic field distribution at least in one direction perpendicularly to the propagation direction of the microwave radiation in the microwave guide.

Abstract: A method for manufacturing a preform for optical fibers by means of a vapour deposition process, wherein plasma conditions are created and wherein the plasma is moved back and forth along the longitudinal axis of the hollow substrate tube between a reversal point near the supply side and a reversal point near the discharge side of the hollow substrate tube, so that the location where the soot deposition associated with one phase takes place is axially spaced from the location where the soot deposition associated with the other phase(s) takes place.

Abstract: The present invention relates to a method for manufacturing a preform for optical fibres by means of a vapour deposition process, wherein plasma conditions are created, and wherein the plasma is moved back and forth along the longitudinal axis of the hollow substrate tube between a reversal point near the supply side and a reversal point near the discharge side of the hollow substrate tube, wherein a transition deposition is carried out between the deposition of one phase and the deposition of the other phase.